Substituted phenylthioamidines

ABSTRACT

1. A SUBSTITUTED PHENYLTHIO AMIDINE COMPOUND OF THE FORMULA:   R-(1,4-PHENYLENE)-S-CH2-C(-NH)=N-OH   WHEREIN R REPRESENTS HALO OR A SALT THEREOF WITH A PHARMACEUTICALLY ACCEPTABLE ACID.

SUBSTITUTED PHENYLTHIOAMIDINE Earl R. Bockstahler, Indianapolis, Ind.,assignor to The Dow Chemical Company, Midland, Mich.

No Drawing. Original application May 30, 1973, Ser. No. 257,940, nowPatent No. 3,775,478. Divided and this application Sept. 27, 1973, Ser.No. 401,475

Int. Cl. C07c 123/00 US. Cl. 260-564 G 2 Claims ABSTRACT OF THEDISCLOSURE Substituted phenylthioamidine compounds such as 2-(4-chlorophenylthio)acetamidine; 2- (4-chlorophenylthio) acetamidoxime; andtheir pharmaceutically-acceptable salts are prepared by the reaction ofa substituted phenylthioacetonitrile with hydroxylamine hydrochloride orwith methanol followed by ammonium chloride. The compounds haveantimicrobial activity and also inhibit ADP- induced aggregation ofblood platelets.

CROSS-REFERENCE TO RELATED APPLICATION This is a division of applicationSer. No. 257,940, filed May 30, 1973, now Patent No. 3,775,478.

BACKGROUND OF THE INVENTION Description of the Prior Art The substitutedphenylthioamidine compounds of the invention can be prepared byprocedures analogous to known methods. Typical methods which can beemployed include the reaction of an arylthioacetonitrile withhydroxylamine hydrochloride in a procedure similar to that of.Bruderlein, US. Pat. No. 3,334,137, or the reaction of aphenylthioacetonitrile with methanol in the presence of sodiummethylate, followed by reaction with ammonium chloride, in a procedureanalogous to that of Schaefer and Peters, J. Org. Chem. 26, 412 (1961).

SUMMARY OF THE INVENTION This invention is directed to substitutedarylthioamidine compounds and is particularly directed to substitutedphenylthioacetamidine compounds and their pharmaceutically-acceptablesalts, the compounds corresponding to the formula:

wherein R represents tertiary butyl (tert-butyl) or halo and Xrepresents hydrogen or hydroxyl. The compounds of the invention aresolids or viscous liquids at ordinary temperatures, and are variouslysoluble in conventional solvents such as water, alcohols, ether,benzene, chlorinated hydrocarbons and the like. The free base compoundsare generally less soluble in water than the salts, particularly underalkaline conditions, while the pharmaceutically-acceptable salts aregenerally of moderate to good solubility in water and alcohols.

:In the present specification, the term halo is employed to designateone of the halogen moieties, fluoro, chloro, bromo or iodo. Thecompounds of the invention wherein X is hydroxyl are named asacetamidoximes. For convenience, both the acetamidines and correspondingoximes can be referred to generically as substituted amidines. The term"pharmaceutically-acceptable salt as herein employed refers to salts ofa substituted amidine which are substantially non-toxic at dosagesconsistent with good pharmacological activity. Suchpharmaceutically-acceptable salts include non-toxic acid addition saltsof pharmaceutically-acceptable acids, i.e. with inor- United StatesPatent ganic acids such as hydrochloric, hydrobromic, sulfuric orphosphoric acid, or with organic acids such as acetic, succinic, malic,maleic, tartaric or citric acid, or with organic sulfonic acids such asmethanesulfonic or p-toluenesulfonic acid.

The substituted amidines of the invention have been found to be usefulfor administration to laboratory animals in the study of drug effects onthe cardiovascular system, and have been found to be particularly usefulin inhibiting aggregation of blood platelets. The compounds wherein R ishalo are highly active against bacterial organisms commonly involved ininfections of the urinary tract, and can be administered orally toanimals to impart antimicrobial activity to the urine in combattingmicroorganisms such as Ps. aeruginosa, E. coli and Proteus vulgaris,organisms commonly involved in urinary tract infections.

The substituted amidines of the invention are prepared by the reactionof the corresponding substituted phenylthioacetonitrile withhydroxylamine in aqueous alcohol (to prepare the acetamidoximes), orwith methanol in the presence of sodium methylate to prepare thecorresponding imidate followed by reaction of the imidate intermediatewith aqueous ammonium carbonate.

In preparing the acetamidoximes, the reaction proceeds when thesubstituted phenylthioacetonitrile and hydroxylamine are contacted andmixed in the presence of a base such as sodium carbonate, and an inertliquid reaction medium such as aqueous ethanol. The reaction proceeds attemperatures from about 50 C. to about C. and is preferably carried outat temperatures of from about 65 C. to about 70 C. The exact proportionsof the reactants to be employed can be varied, however, the reactionconsumes the reactants in equimolar proportions and the use of thereactants in such proportions, or with a slight excess of thehydroxylamine reactant, is preferred.

Greater than two fold molar excesses of hydroxylamine is neithernecessary nor desirable. The reaction is generally complete in about sixto twelve hours, depending on the temperature employed. The product canbe separated by evaporation of the reaction medium under reducedpressure, taking up the residue in water and aqueous acid to neutralizeremaining base, washing with organic solvents, and adding 'base to makethe mixture alkaline. The amidoxime separates as a solid or an oil whichsolidifies on treatment by conventional techniques such as cooling,trituration, scratching, etc. The solid prod not can be purified byrecrystallization from water, alcohols or the like. Alternatively, theproduct can be converted to a pharmaceutically-acceptable salt andpurified as the salt.

The acetamidines of the invention are conveniently prepared by atwo-step process illustrated below:

in the above formulae, the moiety R has the significance first set outabove.

The tfirst step proceeds when the substituted phenylthioacetonitrile isintimately mixed with methanol and a catalytic amount of sodiummethylate. The reaction proceeds at temperatures of from about C. to 70C., and is conveniently carried out at room temperature. After thereaction mixture had been held for a period sulficient for theproduction of sufiicient amount of the imidate intermediate (generallyfrom about 3 to about 12 hours), an ammonium salt is added to themixture and the mixture is maintained at a temperature within the samereaction temperature range until the second step is substantiallycomplete, generally about 12 to 24 hours at room temperature. Theproduct can be separated by evaporation of the reaction medium, and isobtained as the salt with the anion furnished by the ammonium saltreactant. Ammonium chloride is a preferred ammonium salt reactant,although ammonium salts with other pharmaceutically-acceptable anionscan also be employed to produce other salts, such as the hydrobromide,sulfate, carbonate, etc. The product can be purified by conventionaltechniques such as washing and recrystallization from water, alcohols,dioxane and alcohols, and the like. Alternatively, it can be convertedto the free base.

The pharmaceutically-acceptable salts of the free base substitutedamidines can be prepared by dissolving the free base in a minimal amountof alcohol or ether and adding an alcohol solution of an acid such ashydrochloric acid, hydrobromic acid, malic acid, maleic acid or succinicacid until precipitation of the corresponding salt is complete. The saltcan further be purified by recrystallization or converted to the freebase form.

The free base substituted amidine can be prepared by hydrolysis of thesalt in aqueous base. The salt is mixed with a molar equivalent amountof sodium hydroxide in aqueous solution, excess aqueous sodium carbonateor the like, after which the free base can be separated by extractionwith an organic solvent. The solvent can be removed by conventionalmethods such as evaporation or distillation. The product can be purifiedby conventional procedures such as washing or recrystallization.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examplesillustrate the invention but are not to be construed as limiting thesame.

Example 1 10.6 Grams (0.1 mole) of sodium carbonate is dissolved in 40milliliters of water and 16.7 grams (0.24 mole) of hydroxylaminehydrochloride are added. The mixture is then added to a solution of 36.7grams of 4-chlorophenylthioacetonitrile in 350 milliliters of aqueous 95percent ethanol. The resulting mixture is heated with stirring for abouthours at a temperature of 65 70 C., then evaporated to dryness underreduced pressure. The residue is taken up in water and hydrochloric acidis added to make the aqueous mixture slightly acid to litmus. Themixture is filtered, and the filtrate is concentrated by evaporationunder reduced pressure, whereupon the 2 (4chlorophenylthio)acetamidoxime hydrochloride product crystallizes. Theproduct is separated by filtration, and the 2-(4-chlorophenylthio)acetamidoxime hydrochloride product is purified byrecrystallization twice from a mixture of methanol and dioxane, and oncefrom water, and found to melt at a temperature of 153-155 C. The productis found by elemental analysis to have carbon and hydrogen contents of38.2 and 4.3 percent, respectively, as compared to the theoreticalcontents of 38.0 and 4.0 percent, respectively, calculated for the namedstructure.

In a similar procedure, the following acetamidoximes can be prepared:2-(4-bromophenylthio) acetamidoxime, melting at 82-85 C.;2-(4-fluorophenylthio)acetamidoxime hydrochloride (molecular weight236); 2-(4-iodophenylthio)acetamidoxime hydrochloride (molecular 4weight 345); and 2- (4-tert-butylphenylthio)acetamidoxime hydrochloride,melting at 138140 C.

Example 2 0.23 Gram (0.01 mole) of sodium is dispersed carefully in 50milliliters absolute methanol to prepare a mixture of sodium methylatein methanol. 0.1 Mole (18.4 grams) of 2-(4-chlorophenylthio)acetonitrileis added to the mixture and the resulting mixture is stirred at roomtemperature for about four hours. The methyl 2-(4-chlorophenylthio)acetamidate intermediate thus produced is notseparated. 5.9 Grams (0.11 mole) of ammonium chloride is added directlyto the mixture, and stirring at room temperature is continued for about18 hours. The mixture is evaporated under reduced pressure, and theresidue is purified by recrystallization from Water and then fromethanol, and dried. The 2-(4-chloropheny1thio)acetamidine hydrochlorideproduct is found to melt at a temperature of l94-l96 C. By elementalanalysis, the prodnet is found to have carbon and hydrogen contents of40.4 and 4.5 percent, respectively, as compared to the contents of 40.5and 4.3 percent, respectively, calculated for the named structure.

In a substantially similar procedure,2-(4-tert-butylphenylthio)acetamidine hydrochloride, melting at 181- 182(3.; 2-(4-bromophenylthio)acetamidine hydrochloride, melting at l86--l88C., and the corresponding 4- fluoro and 4-iodo compounds are prepared.

In employing the substituted amidine compounds of the invention in thecontrol of microorganisms such as bacteria, protozoa and fungi, andantimicrobial amount of one or more of the compounds is applied to theorganisms, their habitats or to substrates subject to microbial attack.The compounds can be applied by conventional procedures, such asdusting, drenching, impregnation, spraying, or the like. They can beformulated by conventional procedures to provide antimicrobialcompositions by admixture of one or more acetamidine compounds of theinvention with an adjuvant such as surface active dispersing agents,inert liquid carriers, finely divided solid carriers, and the like.

In representative, operations, complete inhibition and control ofStaphylococcus aureus, Bacillus subtilis, T richophyton mentagrophytes,Candida pelliculosa, Pullularia pullulans, Ceratocystis z'ps andCephaloascus fragrans is obtained when nutrient agar containing either500 parts of 2-(4-tert-butylphenylthio)acetamidine hydrochloride or2-(4-tert-butylphenylthio)acetamidoxime hydrochloride per million partsof ultimate composition are inoculated with said organisms and incubatedunder con ditions conducive to microbial growth.

In other representative operations, 2-(4-chloro-phenylthio)acetamidinehydrochloride, 2-(4-chlorophenylthio)- acetamidoxime hydrochloride, and2-(4-tert-butylphe'nylthio)acetamidine hydrochloride are found elfectivein inhibiting the adenosine diphosphate (ADP)-induced aggregation ofsheep platelets in a method similar to that of Zucker et al., Thromb,Diath. Haemorrh. 18, 713 (1967). Said compounds are also found toprotect mice from thrombitic response induced by intravenousadministration of 0.25 millimoles per kilogram of ADP, when thecompounds are administered intragastrically one hour beforeadministration of the ADP challenge. The abovenamed compounds are foundto have ED-SOs (dosage protecting 50 percent of the mice from ADPchallenge) of 40, 71, 160, 57, and 47 milligrams, respectively, of testcompound per kilogram of animal body weight.

In other operations 2-(4-chlorophenylthio)acetamidine hydrochloride and2-(4-chlorophenylthio)acetamidoxime hydrochloride are administeredorally to separate groups discs are then placed on the surface ofnutrient agar media seeded with one of E. coli, Ps. aeruginosa andProteus species and the plates are incubated under conditions conduciveto microbial growth Zones of inhibition of microbial growth 12, 8 and 8millimeters in radial length are observed for E. coil, Ps. aeruginosaand Proteus vulgarz's with test compounds2-(4-chlorophenylthio)acetamidine hydrochloride, and zones 20, 24 and 19millimeters in radial length are observed with the corresponding oximetest compound. In identical operations, no inhibition of any of the testorganisms is observed with 2-(4- chlorophenoxy)acetamidine hydrochlorideof Cummings et al. Chemical Abstracts 44, 8397, (1950) or. itscorresponding oxime; with the 2-(4-methylphenylthio) acetamidinehydrochloride of Craver et al., J. Pharmacol. Exptl. Therap. 99, 353(1950), or the corresponding oxime.

The substituted phenylthioacetonitrile starting materials can beprepared by the reaction of the corresponding thiophenol withchloroacetonitrile in alcoholic sodium hydroxide. In a representativeprocedure, a solution of 100 grams of 4-tert-butylthiophenol and 45.3grams chloroacetonitrile in 225 milliliters of 95 percent ethanol isstirred at room temperature while a sollution of 24 grams sodiumhydroxide in 36 milliliters water is added dropwise until the mixtureremains alkaline to phenolphthalein. Slight spontaneous warming occursduring the addition. The mixture is then diluted with an equal volume ofwater and extracted twice with ether. The ether extract is washed withwater, dried over sodium sulfate, and distilled, yielding the2-(4-tert-butylphenylthio) acetonitrile as a liquid boiling at 153 -6 C.under a pressure of 4 millimeters of mercury.

What is claimed is:

1. A substituted phenylthio amidine compound of the formula:

N-OH y RSCHz-C\ wherein R represents halo or a salt thereof with apharmaceutically acceptable acid.

2. A compound of Claim 1 wherein the compound is2-(4-chlorophenylthio)acetamidoxime hydrochloride.

References Cited UNITED STATES PATENTS 3,334,137 8/1967 Bruderlein260--564 G 3,394,181 7/1968 Bell 260564 G BERNARD HELFIN, PrimaryExaminer G. A. SCHWARTZ, Assistant Examiner US. Cl. X.R. 260501 14

1. A SUBSTITUTED PHENYLTHIO AMIDINE COMPOUND OF THE FORMULA: